Some of my favorites are Harmor, (I just love the sound of this for bassline, with its additive subtractive nature (sounds like a ripping saw when the filter is open and a deep subby sine when you close it)) Absynth, (for its amazing capabilities to make ambient sounds and beautiful pads, just something about the fx section in this synth that hits the spot just right) Zebra2 (for all of the above and everything in between, you just have to have this one really)
With that said, I couldn't live with just those 3, as I have plenty more but if I had to choose a few, those would probably be the ones.